A powerful storm wreaked havoc on the Arctic sea ice cover in August 2012. This visualization shows the strength and direction of the winds and their impact on the ice: the red vectors represent the fastest winds, while blue vectors stand for slower winds. Credit: NASA/Goddard Science Visualization Studio

Published on Sep 19, 2012 by NASAexplorerWatch how the winds of a large Arctic cyclone broke up the thinning sea ice cover of the Arctic Ocean in early August 2012. The storm likely contributed to the ice cap's shrinking to the smallest recorded extent in the past three decades.

The frozen cap of the Arctic Ocean likely reached its annual summertime minimum extent and broke a new record low on Sept. 16, the National Snow and Ice Data Center (NSIDC) at the University of Colorado in Boulder has reported. Analysis of satellite data by NASA and the NASA-supported NSIDC showed that the sea ice extent shrunk to 1.32 million square miles (3.41 million square kilometers), or 293,000 square miles less than the previous lowest extent in the satellite record, set in mid-September, 2007.

"Climate models have predicted a retreat of the Arctic sea ice; but the actual retreat has proven to be much more rapid than the predictions," said Claire Parkinson, a climate scientist at NASA Goddard Space Flight Center, Greenbelt, Md. "There continues to be considerable interannual variability in the sea ice cover, but the long-term retreat is quite apparent."

This year, the cyclone formed off the coast of Alaska and moved on Aug. 5 to the center of the Arctic Ocean, where it churned the weakened ice cover for several days. The storm cut off a large section of sea ice north of the Chukchi Sea and pushed it south to warmer waters that made it melt entirely. It also broke vast extensions of ice into smaller pieces more likely to melt.

"The storm definitely seems to have played a role in this year's unusually large retreat of the ice," Parkinson said. "But that exact same storm, had it occurred decades ago when the ice was thicker and more extensive, likely wouldn't have had as prominent an impact, because the ice wasn't as vulnerable then as it is now.".

Sea ice data courtesy of the Defense Meteorological Satellite Program. Wind data courtesy of the National Centers for Environmental Prediction.

Early in the month of August, 2012, storms in the Arctic affected the motion of the sea ice north of Siberia and Alaska. This animation shows the motion of the winds over the Arctic in conjunction with seasonal melting of the Arctic sea ice from August 1 through September 13, 2012, when the NASA scientists determined that the sea ice reached its annual minimum extent. The surface winds, shown my moving arrows, are colored by the velocity. Slower winds are shown in blue, medium in green and the fast winds are shown in red.

Note: Scientists at the National Snow and Ice Data Center, who calculate the sea ice minimum based on a 5-day trailing average, identified September 16 as the date when the lowest minimum extent occurred. NASA scientists who calculate area on each individual day identified September 13th as the date of the minimum sea ice, although there is little difference in size between the two days.